1. Field of the Invention
The present invention relates to a data transmitting equipment carrying out data transmission via a communication line.
2. Prior art
Data transmission equipment sending and receiving data between a desired remote equipment via a communication line is known. Hand in hand with the beginning of ISDN service (Integrated Service Digital Network) and because of the possibility of high speed transmission of any unprocessed digital data, the development of data transmitting equipment making use of this has been advanced. When data transmission is done via communication lines, confirmation of the identity of the communication partner is difficult and therefore, originally, there is a danger that data are erroneously transmitted to a party not qualified for receiving data. One of the methods for preventing data transmissions to a party having no reception qualifications, is the use of a password. This means that a password is to be decided beforehand between the party sending the data and the legitimate receiver of the data. Then, before starting to transmit data, sender and receiver respectively have to input the password in the data transmitting equipment and the passwords of both parties are compared via a communication line, and only when the passwords of the two sides are consistent, data supply from the sender's side to the receiver's side is permitted.
In data transmitting equipment of prior art the input password was maintained in the data transmitting equipment after the end of the data transmission. In case the user forgets to eliminate the password, the problem is, that the password is exposed to another person using the data transmitting equipment thereafter. For avoiding this exposure the user always has to worry about the delete of the password.